There have been many different types and kinds of mass production techniques for mounting surface mount devices, such as an integrated circuit device, to a printed circuit board. One such technique is a hot bar reflow soldering system. In this system, the surface mount devices to be installed are transported from one location to another during the course of assembling them in the desired locations on a printed circuit board.
Such reflow soldering systems typically employ pick and place systems operated under the control of a robotic unit to retrieve the devices seriatim from one location, and then position them at desired locations on the printed circuit board, so they may be affixed thereto by suitable bonding techniques, such as adhesive and reflow soldering techniques. An important aspect of such surface mount technology includes the removal of such devices intact from the printed circuit board in the event of device failure. In this regard, if the flimsy lead bearing type of the devices are ripped or torn or if the closely spaced leads of the miniature devices are damaged during removal from the printed circuit board, the devices can not be priory tested for determining failure causes. Moreover, if residue device debris, such as lead or tape debris, remains affixed to the printed circuit board, time consuming cleaning operations can result. Thus, costly and unwanted quality control and claiming operations can result.
While such prior known systems have been satisfactory for mounting integrated circuit devices to printed circuit boards, the problems experienced in damaging such devices when they are removed from the printed circuit board have occurred all too frequently. In this regard, in removing the device from the printed circuit board all too often the device or the leads of the device are damaged.
One attempted solution to solve the above-mentioned problem, has been the use of a solder wick, such as disclosed in U.S. Pat. No. 4,934,582 to remove excess solder from the leads of the device to facilitate its removal from the printed circuit board. While the solder wick technique helps to remove solder from the leads of the device, the technique does not entirely eliminate device and board damage particularly when attempting the removal of a fine pitch device to the printed circuit board pads. In this regard, in order to protect fine pitch devices from damage when they are initially being mounted to the printed circuit board, a heat sink or a heat sink type binder with hub metal content is utilized for dissipating thermal energy away from the device. Such a binder however adheres the body of the integrated circuit device to the printed circuit board. Thus, even if solder from the outer leads of the devices is removed the miniature body of the device with its small delicate and closely spaced inner leads still remains adhered to the printed circuit board.
Another attempt to solve the above-mentioned problem has been the use of a hot bar and tweezers to detach the body of the device form the printed circuit board. This technique has proven to be less than satisfactory. In this regard, while using a hot bar on top of the integrated circuit device loosen the bond of the adhesive, the thermal energy transferred through the device all too often damages its delicate circuits. Moreover, even if the delicate circuits are not damaged using the tweezers to remove the device from the printed circuit board is microscopic time consuming tedious work and many times results in the delicate leads of the device being damaged by the tongs of the tweezers.
Still yet another attempted solution to solve the above mentioned problem has been the use of a vacuum actuated center quill device to grip the body of the integrated circuit device once the body has been sufficiently heated to loosen the bonding material. In this regard, when the bonding material is loosened, the center quill grips the body holding it firmly as a robotic unit attached to the center quill moves the center quill away from the device causing the device to be removed from the printed circuit board. While this technique has proven satisfactory with larger integrated devices, it has proven less than satisfactory with the smaller fine pitch devices because the smaller body surface areas of such devices is generally so small, that the vacuum actuated center quill loses its ability to sufficiently grab the device so that it may be lifted from the printed circuit board.
Therefore, it would be highly desirable to have a new and improved chip removal method and system for detaching an integrated circuit device from a printed circuit board. Such a system and method should greatly reduce, or even substantially eliminate damaging the integrated circuit device during removal, so that the device may be tested after removal for determining primary device failure cause. Moreover, such a method and system should not only be highly effective, but it should also be efficient, by enabling both large and small fine pitch devices to be picked up intact directly from the printed circuit board and mounted for easy testing purposes.